Organic natural fibers such as wood fibres are currently widely used for making composite panels and are widely used for thermal insulation applications, in particular composite wood panels. Composite wood panels in general are very attractive in construction industry because of their self-supporting properties and mechanical strength. Composite wood board products such as particleboard, medium density fiberboard (MDF), high density fiberboard (HDF) and oriented strand board (OSB) are used in many applications such as home roofing and flooring, furniture, cabinets, door panels, frames, signposts, . . . . Generally, to make such composite products a particulate lignocellulosic (wood) substrate is mixed with a binder, and the mixture is put on a mat or other surface for pressing. WO 2008/144770, WO 2010/147936 and WO 2013/012845 describe methods to fabricate composite wood panels.
However, for thermal insulation applications, ideally the lambda value (thermal conductivity) of composite wood panels should be further improved in order to compete with existing super-insulator materials (which have significantly better lambda values e.g. 20-30 mW/m·K at 10° C. for polyurethane rigid foams).
Recent developments in further improving the insulation value for wood fibre insulation boards resulted in thermal conductivity values (i.e. lambda values) ranging between 35 and 50 mW/m·K at 10° C. under atmospheric pressure, depending mainly on panel density (ranging typically from 40 to 200 kg/m3). The lambda value is usually decreased to some extent by decreasing density. For instance, a panel of density 200 kg/m3 typically has a lambda value around 50 mW/m·K, while a panel of density 40 kg/m3 typically has a lambda value around 35 mW/m·K. With this approach, a lambda value of about 35 mW/m·K is the minimum which can be achieved. Going further down in density would result not only in panels with increased lambda values but also with poor mechanical properties (e.g. limited structural integrity).
There is a need to develop a fabrication method to further improve significantly the thermal insulation properties of insulation materials (e.g. panels) based on organic natural fibers such as composite wood panels. To fulfil the properties of the construction industry these materials ideally should be self-supporting and have excellent mechanical properties.
It is a challenge to further improve significantly the thermal insulation properties of insulation materials (panels) based on organic natural fibers such as composite wood panels towards lambda values lower than 35 mW/m·K, preferably in the range 15-30 mW/m·K (measured at 10° C.) without deteriorating the mechanical strength of the materials.
Goal of the Invention
It is the goal of the invention to develop a composite material which has beside excellent thermal insulation properties also good mechanical and self-supporting properties.
It is a further goal to fabricate a composite material comprising organic natural fibers and more than 25% by weight nanoporous particles, said composite material having light weight, good mechanical properties, self-supporting properties and a low lambda value.
It is a further goal to develop a binder composition and a processing method to combine the organic natural fibers (preferably in the form of wood fibres) and the nanoporous particles such that a novel composite material is created having improved mechanical properties, self-supporting properties and a low lambda value compared to state of the art composites comprising organic natural fibers.
Therefore, the present invention relates to a novel composite material, a novel binder composition based on emulsifiable polyisocyanate, a novel processing method to fabricate the novel composite and use of the novel composite material for thermal and/or acoustic insulation.